An optical waveguide can comprise two longitudinally extending materials with different refractive indices that adjoin or contact one another to form an optical interface running lengthwise. The interface can be internally reflective as a result of a refractive index differential between the two materials. The interface can reflect light propagating along the high-refractive index material that is incident upon the interface. For example, a multimode or single mode optical fiber can comprise a cladding and a core, with the cladding adjoining and/or circumferentially surrounding the core and having a lower refractive index than the core. Such a basic architecture can be adapted for numerous applications, like illumination systems, head-mounted surgery lights, light pipes, endoscopes, single-mode optical fibers, communication optical fibers, multimode optical fibers, fiber optic sensors, planar lightguide circuits (“PLCs,” also known as “planar lightwave circuits”), and optical buses, to name a few examples.
In many instances, the refractive index differential between the two materials establishes, defines, influences, or sets light propagation characteristics of the optical waveguide. For example, an optical fiber's numerical aperture can be a function of the respective refractive indices of the fiber's core and cladding, with a high refractive index differential supporting a high numerical aperture. Thus, increasing the refractive index differential facilitates accepting, emitting, and/or transmitting light of greater angular orientation.
In many situations, silica, silicate, silicon dioxide, glass, or glassy material provides a desirable material for a core of an optical waveguide. Such a core can be coated with a polymer having a refractive index lower than that of the core to form a clad waveguide. However, conventional polymer-based cladding materials generally have a limited range of refractive indices, without supporting a refractive index that is as low as would be desirable for many applications. Accordingly, conventional waveguide technologies are often lacking in terms of receiving, guiding, and/or delivering light that is oriented at aggressive angles relative to an optical waveguide's longitudinal axis.
In view of the foregoing discussion of representative deficiencies in the art, need exists for improved optical materials and for improved optical waveguide and fiber optic technologies. Need exists for an optical material system having a refractive index that is low, that is flexible, and/or that can be adapted according to application. Need further exists for high numerical aperture optical fibers and optical waveguides. Need also exists for a technology that can substantially reduce the refractive index of an optical polymer, or other optical material, having otherwise desirable properties, such as desirable optical, mechanical, workability, coating, manufacturability, chemical, stability, or other properties. A technology addressing such a need, or some other related shortcoming in the art, would promote photonic and optical applications.